Bizarre Vortex on Venus Changes Shape Every Day

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A giant vortex at the south pole of Venus is actually a
shape-shifter that changes form at least once a day, at times
bizarrely taking on the appearance of a giant letter "S" or the
number "8," a new study reveals.

Venus, the second closest planet to the sun, possesses giant, hot
and essentially permanent vortexes of clouds whirling fast at its
poles. These result from how Venus' atmosphere circulates much
faster than any other rocky planet's in the solar system — the
cloud-level atmosphere of Venus on average spins 60 times faster
than the planet's surface. [ Photo
of the Venus vortex ]

The vortexes cannot really be called storms, as scientists have
seen neither rain nor lightning in them.

Past images suggested the roughly 1,200-mile-wide
(2,000-kilometer) southern
polar vortex was only a spinning oval shape. However, new
infrared pictures from the Visible and Infrared Thermal Imaging
Spectrometer (VIRTIS) on the European Space Agency's Venus
Express mission revealed far more detail than past images,
showing that the vortex's internal structure changes shape at
least every 24 hours. [ Most
Extreme Planet Facts ]

"Filaments swirl around one or two bright — that is, warmer —
centers," researcher David Luz, a planetary scientist at the
University of Lisbon, told SPACE.com. "Sometimes the shape looks
like an S or an 8, sometimes it shows three bright centers, but
mostly it's irregular."

The vortex is not poised directly over the south pole, but
instead its center is consistently located approximately three
degrees of latitude away, and it drifts around the pole,
completing a circuit every five to 10 days.

These findings suggest the atmospheric dynamics at Venus'
southern pole are more complex than scientists thought. They
suspect the vortexes are fed by air descending from currents
circulating along the meridians over the poles, and the fact the
southern vortex drifts suggest the point of maximum downwelling
is also wandering. [ Infographic:
Inside the Planet Venus ]

"This is a change in our understanding that general circulation
models of Venus will need to take into account," Luz said.

The researchers suspect the vortex at Venus' north pole acts
similarly, "but for the moment we don't know, because Venus
Express' highly elliptical orbit brings it too close to the north
pole, making it impossible to do similar imaging studies," Luz
said. "We can see only a very small region."